Spark plug



March 13, 1945. V McK. FIELD SPARK PLUG Filed Feb. 20, 1942 Patented Mar. 13, 1945 SPARK PLUG Lloyd McKinsey- Field,v Cleveland, Ohio Application February 20, 1942, Serial No. 431,755

11 Claims.

This invention relates to certain new and useful improvements in spark plugs.

In spark plugs of standard construction there is provided a center positive electrode extending through an insulator casing set into a shell with the latter mounted in the wall of an internal combustion engine to present the inner end of such center-fixed electrode together with the negative electrode usually carried by the shell within the combustion chamber of the engine. In the use of such spark plugs of standard construction, the points of the positive andnegative electrodes rapidly become fouled, while the tip of the positive electrode within the combustion chamber rapidly burns away at its point of projection from the insulator casing, thereby rendering theplug useless for further duty and resulting in an extremely expensive loss of the entire plug body.

It is therefore the primary object of the prescut invention to improve the construction and operation of such plugs and to materially prolong the life thereof and to accomplish such object, the center positive electrode is preferably formed of two sections comprising an outer section extending beyond the outer or upper end of the insulator body or casing for the attachment of a conductor, with such outer section terminating in proximity of the inner end of the insulator casing, and an inner relatively shortsection of the positive electrode that is freely movable with in the inner end of the insulator casing for vibratory or reciprocating movements therein for contact with the outer section of the center electrade and for cooperation withthe usual under? lying negative electrode usually forming a part of or carried by the shell of the spark'plug.

A further object of the inventionis to provide an improved type of spark plug of theforegoing character and especially for use in the top cylinder lubricant-solvent distributing mechanism in Patent No. 2,229,063 issued on January 21, 1941, to Lloyd lubricant-solvent through the tubular center electrode disclosed herein being operative for cooling and cleaning the contact points of the electrodes with the reciprocating tip of the center section of the electrode constituting the valve for controlling the flow of lubricant-solvent through the plug.

With the above and other objects in view that will become apparent as the nature of the in vention is better understood, the same consists in the novel form, combination and arrangement of parts hereinafter more fully described, shown in the accompanying drawing and claimed.

McKinsey Field, the flow of the In the drawing:

Figure 1 is a longitudinal sectional view of a spark plug constructed in accordance with the present invention with the center positive electrode of tubular or conduit type and having a vibratory or reciprocating firing tip cooperating with the negative electrode, the movable tip being illustrated in a position of rest in supporting contact with the negative electrode during the induction stroke of the piston of an internal combustion engine,

Figure 2 is an enlarged fragmentary sectional view of the lower end of the spark plu shown. in Figure 1 and illustrating the movable firing tip of the center electrode in valve-seating position relative to the center tubular electrode during the compression stroke of the engine piston and in spaced firing position relative to the negative electrode,

Figure 3 is a longitudinal sectional view of another type of spark plug embodying a solid sectional center electrode with the inner vibratory or reciprocating firing tip section of the center electrode seated upon the negative electrode during the induction stroke of the engine piston,

Figure 4 is an enlarged detail sectional view of the inner end of the spark plug shown in Figure 3 and illustratingthe movable firing tip of the center electrode engaged with the fixed section of the center electrode and in spaced. firing relation to the negative electrode during the compression stroke of. the engine piston,

Figure 5 is a detail sectional view of 'a modified construction of the spark plug shown in Figures l and 2 wherein the fixed center tubular electrode is spaced from the inner terminal end of the insulator casing with the movable center electrode firing tip working in a chamber in the insulator casing, and

Figure 6 is a detail sectional view of spiral form of movable center electrode firing tip that may be used with either a solid or tubular center electrode section. I

Referring more in detail to the accompanying drawing and particularly to Figures 1 and 2, there is illustrated a spark plug especially designed for use with the top cylinder lubricantsolvent distributing mechanism disclosed in the patent previously identified herein, said plug com- H prising an insulator casing in shouldered in the usual manner for seating and interfitting mounting in the metallic shell H for retention therein by the usual follower nut l2. The lower end of the shell I I is annularly reducedand externally threaded as at I3 for mounting in the cylinder wall or head of an internal combustion engine to present the positive and negative electrodes of the spark plug within the combustion chamber of the engine. The usual annular negative electrode M is carried by the inner end of the shell H and extends across the longitudinal axis of the spark plug and while the drawing illustrates the negative electrode 14 as a separate element from the shell, it is to be understood that the shell which forms the ground or negative may have a portion thereof formed to provide the negative electrode.

The insulator casing in is longitudinally and axially bored for the reception of a tubular or conduit type center positive electrode I5, the inner end of the center electrode 15 as illustrated in Figures 1 and 2 terminating flush with the inner end of the insulator casing l while the outer end of the center electrode l5 extends outwardly beyond the outer end of the insulator casing.

The center tubular electrode I5 is of sectional form, the inner end thereof for a relatively short distance having the passage therethrough annularly enlarged to provide a chamber IS, with the inner end of the bore through the tubular electrode and at the outer end of the chamber l6 constituting a valve seat H. The tubular center electrode I5 being of the sectional type includes a vibratory or reciprocating firing electrode tip l8 freely movable within the chamber l3 and preferably carrying an enlarged head l9 at its inner terminal end for cooperation with the un derlying negative electrode l4. The upper end of the firing tip l8 of the center electrode is illustrated as being of conical formation as at 20 to constitute a valve for engaging the valve seat I! and while this valve end 20 is illustrated as being conical, it is understood that the same may be of any shape or configuration desired.

For the supply of fluid or a lubricant-solvent to the center tubular electrode I5 and to accommodate the attachment thereto of a conductor wire, a conical block 2| is sweated or otherwise anchored upon the upper projecting end of the electrode IS in engagement with theupper end of the insulator casing as shown in Figure l,

the conical block and that portion of the center electrode surrounded thereby having a transverse port 22 therethrough, while the upper end of the bore of the tubular electrode terminates at and communicates with said transverse port.

A shell cap 23 is seated on the conical block 2! and carries diametrically opposite tubular nipples 24 communicating with the chamber 25 in the shell cap 23 and-the transverse port 22, the shell cap 23 being retained in position on the conical block by means of the tubular follower nut 26.threaded upon the upper end of the center electrode l5 and to which nut 26 the usual conductor wire is attached. It is understood that the nipples 24 f the shell caps 23 of adjacent spark plugs are connected by flexible conduits firing tip sections.

of two sections, the outer elongated center electrode section l5 comprising a solid rod and terminating in spaced relation at its inner end to the inner terminal end of the insulator casing Ill The vibratory or reciprocating inner firing tip section I8 of the center electrode is movable in the chamber I6 that is formed by the Wall of the insulator casing, the movable firing tip l8 during the induction stroke of the engine piston resting upon the negative electrode l4 with the upper conical end 2i) spaced of the inner terminal end of the fixed center electrode section 15. Figure 4 of the drawing shows the movable electrode firing tip section H3 in the position assumed during the compression stroke of the engine piston, the movable section l8 being spaced from the negative electrode W the usual spark gap distance while its upper conical end is engaged with the fixed center electrode section l5 for the conduct or fiow of current. It is to be understood that the upper conical end 20 of the movable center electrode section l8 may be fiat or assume any configuration desired.

In the operation of the two forms of spark plugs'and in particular the movable firin'g tip sections l8 or If! of the center electrodes, it will be understood that during the induction stroke of the engine piston the movable firing tip is moved downwardly through the chambers at the inner ends of the center electrodes and forcibly contact the negative electrode, such action tending to remove any carbon deposit on both the positive and negative electrodes and maintain the points of firing contact in a clean condition. In the conduit type of spark plug illustrated in Figures 1 and 2, the flow of lubricantsolvent in addition to breaking off any carbon deposit from the firing points of the electrodes also tends to cool the electrodes. The relative diameters of the movable firing tip sections of the center electrodes and the walls of the chambers l6 or l6 are such as to 'provide suflicient clearance for free movements of the movable Such diameters are so proportioned as to eliminate any undue pressures in the chambers which would mitigate against the contact of the movable firing tip of the center electrode with the fixed center electrode section. In the use of spark plugs it is usually so that a source of lubricant-solvent may be delivered to the entire set of spark plugs of an internal combustion engine.

In the form of invention illustrated in Figures 3 and 4, the general construction of the main elements of the sparkplug are the same as those illustrated in Figures 1 and 2, the insulator casing Ill being seated in the metallic shell ll and retained therein by the follower nut I2 the lower threaded end l3 of the shell supporting the negative electrode 14 In this form of spark plug, the center electrode is formed the firing tip portion of the center electrode that soon burns away and thus destroys the life of the entire plug. By providing the movable firing tip section at the inner end of the center electrode, the normal life of the plug is greatly increased by reason of the prevention of encrustation occasioned by the multiple contacts effected between the movable firing tip section and the negative electrode. However, when the movable tip section becomes unduly worn it is only necessary to bend or twist the inner end of the negative electrode l4 out of the longitudinal axis of the center electrode for the removal of the burnt firing tip section and the replacement of a new one, the negative electrode M or I4 being then restored to its correct position and firing gap relative to the movable firing tip section of the center electrode. Except for damage or injury to the insulator body portion of the plugs, the life thereof is indefinite and by reasvmee l 3 tubular center electrode I 5 terminates at its lower. end in spaced relation to the lower or inner end of the insulator body lo the body Hl having a chamber It therein extending from the lower end ofsaid body to the adjacent end of theelectrode l5 and of lesser diameter than the head l9 thereof cooperating with the negative electrode M It will be understood that the upper end of the firing tip section it constitutes the valve for closing thelower end of the passage through the tubular center electrode section 15*.

In the form of invention illustrated in Figure 6,

the general structure thereof is comparable with the form of invention illustrated in Figures 3 and l and includes a solid center electrode rod section 15 terminating in spaced relation to the innerv or lower end of the insulator body [0 to provide a chamber Hi in the lower end of the insulator body for the vibratory or reciprocablemounting of the firing tip electrode section 18 which cooperates with the negative electrode Id".

The firing tip center electrode section 18 is spirally grooved and in addition to normal reciprocatory movements thereof, engine impulses will produce rotary activities to insure the main tenance of clean contact surfaces between the electrodesections I 8 and M The spiral groove 19 in the firing tip section [89.may gather carbon deposits'which will act as a packing seal in working in chamber I6 From the above detailed description of the invention, it is believed that the construction and operation thereof will at once be apparent and while there are herein shown and described the preferred embodiments of the invention, it is nevertheless to be understood that minor changes may be made therein without departing from the spirit and scope of the invention as claimed.

I claim:

1. In a spark plug of the character described, a shell and insulator body, a center positive electrode and a negative electrode associated with the shell, said center electrode being formed of sections with one of the sections stationary and the other section being free floating and cooperating withv the negative electrode and being reciprocated in response to engine pulsations, said free floating section of the center electrode being unsupported and unguided at its upper end relative to the stationary section of the center electrode.

2. In a spark plug of the character described, a shell and insulator body, a center positive electrode and a negative electrode associated with the shell, said center electrodeincluding a free floating vibratory firing tip, the stationary sec-' tion of the center, electrode being of the conduit type for the flow of lubricant therethrough to the combustion chamber of an internal combustion engine and the firing tip portion of the center electrode forming a closure valve for the conduit during compression in an engine cylinder, the vibratory tip being unsupported relative to I the other portion of the center electrode, and

said negative electrode forming a retainer seat for said firing tip.

3. In a spark plug of the character described, a

shell and insulator body, a center positive electrode and a negative electrode associated with the shell, said center electrode being formed of sections with one of the sections stationary and the other section being free floating and cooperating with the negative electrode and in operation being reciprocated in response to engine pulsations, said free floating section of the electrode beingunsupported and unguided at its upper end relative to the stationary section of the center electrode, the stationary section of the center electrode being of the conduit type for the flow of fluid therethrough to the combustion chamber of an internal combustion engine and the firing tip portion of the center electrode forming a closure valve for'the conduit during compression in an engine cylinder, said firing tip being retained within its chambered position by said negative electrode when the valve is .in open position.

4. In a spark plug of the character described, a shell and insulator body, a center positive electrode and a negative electrode associated with the shell, said center electrode including a vibratory firing tip, thestationary section of the center electrode being of the conduit type for the flow of fluid therethrough to the combustion chamber of an internal combustion engine and the firing tip portion of the center electrode forming a closure valve for the conduit during compression in an engine cylinder, the inner end of the conduit through the center electrode being annularly enlarged to form a chamberv for mounting the firing tip.

5. In a spark plug of the character described,

a shell and insulator body, a center positive electrode and a negative electrode associated with the shell, said center electrode being formed of sections With one of the sections stationary andthe other section cooperating with the negative electrode and being reciprocated in response to engine pulsations, the stationary section of the center electrode being of the conduit type for the flow of lubricant therethrough to the, combustion chamber of an internal combustion engine and the firing tip portion of the center electrode forming a closure valve for the conduit during compression in an engine cylinder, the inner end of the conduit through the center electrode being annularly enlarged to form a chamber for mounting the firing tip.

6. In a spark plug of the character described, a shell'and insulator body, a center positive electrode and a negative electrode associated with the shell, said center electrode including a free floating vibratory firing tip, the stationary section of the center electrode being of the conduit type for the flow of lubricant therethrough to the combustion chamber of an internal combustion engine'and the firing tip portion of the centhe inner end of the center electrode terminating in spaced relation to the inner end of the insulator body providing a chamber in the insulator body for the placement of the firing tip.

7. In a spark plug of the character described,

. a shell andinsulator body, a center positive electrode and a negative electrode associated with the shell, said center electrode being formed of sections with one of the sections stationary and the other section being free floating and cooperating with the negative electrode and being reciprocated in response to engine pulsations, said free floating section of the center electrode being unsupported and unguided at its upper end relative to the stationary section of the center electrode, the stationary'section of the center electrode being of the conduit type for the flow of lubricant therethrough to the combustion chamber of an internal combustion engine and the firing tip portion of the center electrode forming a closure valve for the conduit during compression in an engine cylinder, the inner end of the center electrode terminating in spaced relation to the inner-end of the insulator body providing a chamber in the insulator body for the placement of the firing tip.

8. In a spark plug of the character described, a shell and insulator body, a center positive electrode and a negative electrode associated with the shell, said center electrode including a free floating vibratory firing tip, the stationary section of the center electrode comprising a solid rod and terminating inwardly of the inner end of the insulator body to provide a chamber in the insulator body for the placement of the firing tip, the vibratory tip being unsupported relative to the other portion of the center electrode.

9. In a spark plug of the character described, a shell and insulator body, a center positive electrode and a negative electrode associated with the shell, said center electrode being formed of sections with one of the sections stationary and the other section being free floating and cooperating with the negative electrode and being reciprocated in response to engine pulsations, said free floating section of the center electrode being unsupported and unguided at its upper end relative to the stationary section of the center electrode, the stationary section of. the center electrode comprising a solid rod and terminating inwardly of the inner end of the insulator body to provide a chamber in the insulator body for the placement of the firing tip.

10. In a spark plug of the character described, a shell and insulator body, a center positive electrode and a negative electrode associated with the shell. said center electrode including a vibratory firing tip, the stationary section of the center electrode comprising a solid rod terminating inwardly of the inner end of the insulator body to provide a chamber in the insulator body for the placement of the firing tip, and said firing tip being positioned entirely inwardly of the stationary section of the center electrode and spirally grooved whereby engine pulsations efiect reciprocatory and rotary movements thereof for maintaining carbon free contact faces between the firing tip of the center electrode and the negative electrode.

11. In a spark plug of the character described, a shell and insulator body, a center positive electrode and a negative electrode associated with the shell, said center electrode being formed of sections with one of the sections stationary and the other section cooperating with the negative electrode and being reciprocated in response to engine pulsations, the stationary section of the center electrode comprising a solid rod terminating inwardly of the inner end of the insulator body to provide a chamber in the insulator body for the placement of the firing tip, and said firing tip being positioned entirely inwardly of the stationary section of the center electrode and spirally grooved whereby engine pulsations effect reciprocatory and rotary movements thereof for maintaining carbon free contact faces between the firing tip of the center electrode and the negative electrode.

LLOYD McKINSEY FIELD. 

